Catalytic reforming process

ABSTRACT

A catalytic reforming process wherein naphtha feed streams, boiling from about 80* to 450* F, and comprising naphthenes, paraffins and aromatics, are contacted, in an initial reaction zone, with a hydrogen containing gas, in the presence of a catalyst comprising Pt and a group IB metal supported on a refractory oxide; passed into a tail zone wherein the feed stream is again contacted with a catalyst and thereby further reacted; and a high octane product is recovered. In a preferred embodiment the Group IB metal is Cu.

Unite States ate Carter et a1.

[ 1 Apr. 24, 1973 CATALYTIC REFORMING PROCESS [73] Assignee: EssoResearch and Engineering Company, Linden, NJ.

22 Filed: Dec. 28, 1970 21 Appl.N0.: 102,208

[52] U.S. Cl. ..208/65, 208/138, 252/474,

252/466 PT [51] Int. Cl. ..C10g 35/08, BOlj 11/08, BOlj 1l/22 [58] Fieldof Search ..208/138, 65;

[56] References Cited UNITED STATES PATENTS 2,911,357 l1/1959 Myers etal ..208/138 3,576,736 4/1971 Kittrell ..252/474 3,198,728 8/1965 Evans3,442,973 5/1969 Sinfelt et a1. 3,567,625 3/1971 Sinfelt et a1...208/138 Primary ExaminerDaniel E. Wyman Assistant ExaminerWerten F W.Bellamy Att0rneyChasan & Sinnock and John P. Corcoran [57] ABSTRACT Acatalytic reforming process wherein naphtha feed streams, boiling fromabout 80 to 450 F, and comprising naphthenes, paraffins and aromatics,are contacted, in an initial reaction zone, with a hydrogen containinggas, in the presence of a catalyst comprising Pt and a group lB metalsupported on a refractory oxide; passed into a tail zone wherein thefeed stream is again contacted with a catalyst and thereby furtherreacted; and a high octane product is recovered. In a preferredembodiment the Group 18 metal is Cu.

14 Claims, No Drawings CATALYTIC REFORMING PROCESS BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to acatalytic reforming process. More particularly this invention relates toreforming naphtha feed streams boiling from about 80 to 450 F andcomprising naphthenes, paraffins and aromatics in a combination processwherein the feed stream is contacted in an initial reaction zone with ahydrogen containing gas in the presence of a catalyst comprising Pt anda metal selected from Group [B of the Periodic Table of the Elements,supported on a refractory oxide,-then passed into a tail zone whereinthe feed stream is again contacted with a catalyst and thereby furtherreacted, and a high octane product is recovered. Preferably the Group [Bmetal is Cu.

2. Description of the Prior Art Catalytic reforming is now a matter ofrecord and commercial practice in this country. Basically, reforminginvolves the contacting of a naphtha fraction, either virgin, cracked,Fisher-Tropsch or any mixtures thereof, with a solid catalytic material.The catalyst is ordinarily a supported noble metal catalyst, such asplatinum or alumina. Contacting takes place at elevated temperatures andpressures in the presence of added or recycled hydrogen. Hydrogen isessential since it suppresses the deactivation of the catalyst. Theprocess itself produces substantial amounts of hydrogen, and inactuality this is the source of the hydrogen which is recycled torepress the deactivation of the catalyst; the deactivation of thecatalyst is caused at least in part by carbon formation.

Reactions involved in catalytic reforming are: (l) dehydrogenation ofnaphthenes to the corresponding aromatic hydrocarbons such ascyclohexane dehydrogenation to benzene; (2) isomerization of normalparaffins to branched-chain paraffins or isomerization of ringcompounds, such as ethylcyclopentane to methylcyclohexane, which lattercompound readily dehydrogenates to form toluene; (3) dehydrocyclizationof paraffins to aromatics, 'e.g., n-heptane to toluene; and (4)hydrocracking of the higher boiling constituents.

Fixed bed catalytic reforming processes may be divided into threegeneral classes: non-regenerative, semLregenerative and cyclic. Thethree processes differ most significantly in that the cyclic has analternate or swing reactor which is so manifolded that it may replaceany reactor within the system in order that the replaced reactor may beregenerated. The instant invention is intended to include all classes ofreforming.

A great variety of catalysts for catalytically reforming a naphtha feedstream is known; perhaps the best known of these catalysts is platinumdispersed upon a highly purified alumina support such as one may obtainfrom aluminum alcoholate. Such a catalyst is described in detail in U.S.Pat. No. 2,636,865, the disclosure of which is herein incorporated byreference. Other members of the platinum group such as palladium orrhodium may be utilized, but platinum is much preferred. The aluminasupport should have a high surface area, greater than 50 m /gm. Itshould also have acidic properties, and hence must be substantially freeof alkaline impurities.

The reforming system can be considered to consist of two separatereaction zones. In the initial zone, naphthene dehydrogenation andisomerization are the primary reactions. In the tail zone,dehydrocyclization and hydrocracking reactions occur predominantly.

It is noted that commercial reforming systems can be composed of threeto four reactor units in series. These units will together comprise boththe initial reaction zone and the tail zone. It is to be understood thatin the process of this invention the first l, 2 or 3 reactors cancomprise the initial reaction zone and the remaining reactor or reactorscan comprise the tail zone. It has been generally thought that thePt-alumina catalyst is the best available for the reactions occurring inthe initial zone, and attempts to improve the efficiency of naphthareforming processes have centered on finding catalysts with improvedefficiency for the reactions occurring in the tail zone. In actualpractice with platinum-alumina catalyst, a substantial fraction of thealkylcyclopentanes which are present in the naphtha feed, undergoeshydrogenolysis or hydrocracking reactions in the initial reaction zone,thus limiting the selectivity of conversion of the alkylcyclopentanes tothe desired high octane number aromatic products.

SUMMARY OF THE INVENTION It has now been unexpectedly found that thesubstitution of a Pt-Group IB bimetallic catalyst for the Pt catalystsknown in the art, in the initial reaction zone of a reforming process,greatly increases the selectivity of conversion of alkylcyclopentanes tohigh octane number aromatic products.

The catalyst of this invention comprises Pt and a Group 18 metal on arefractory oxide support. The Group 18 metal is preferably Cu and thesupport is preferably selected from the group consisting of alumina,silica-alumina, crystalline aluminosilicates, and halogen containingalumina. The support is usually acidic and has a high surface area,e.g., 50 to 300 m /g. The support may also contain small amounts ofhalogen, i.e., Cl and F, for added acidity. This halogen may be added tothe support in the catalyst preparation, or it can be added to thecatalyst in situ in the reactor.

The Pt metal comprises about 0.05 to 2.0 wt. percent of the totalcatalyst, preferably 0.1 to 0.6 wt. percent and most preferably 0.25 to0.35 wt. percent. The Group IB metal will comprise 0.05 to 2.0 wt.percent of the total catalyst. In the case of copper, the amount wouldbe preferably 0.1 to 0.6 wt. percent and most preferably 0.25 to 0.35wt. percent. The remaining catalyst weight is supplied by the supportand/or halogen. Halogen may vary from 0.1 to 2.0m. percent, preferablyfrom 0.3 to 1.0 wt. percent of the total catalyst.

The catalyst may be'prepared by impregnating the support with solubleplatinum and Group lB metal salts. A preferred method for preparing thecatalyst is to impregnate the support with an aqueous solution .ofchloroplatinic acid and a salt such as copper nitrate.

While not wishing to be limited by theory, it is believed that thehydrogenolysis (cracking) activity of the catalyst is inhibited byincorporation of the Group 18 metal.

The feed streams which can be successfully treated by the process ofthis invention include naphthas. A naphtha feed stream is a petroleumfraction boiling between about 80 and 450 F., preferably between 120 and40 F., and contains paraffinic, naphthenic and aromatic hydrocarbons. Ingeneral the naphtha feed stream will contain about 15 to 75 percent byweight paraffins, about 15 to 75 percent by weight naphthenes and about2 to 20 percent aromatics.

In the process of this invention, the naphtha feed stream will containto '15 wt. percent naphthenes upon leaving the initial reaction zone,preferably 0 to wt. percent, the remainder consisting of aromatics andparaffins. With the description of the novel process of this invention,it will be possible for the skilled artisan to design a reforming systemto give the maximum yield of high research octane number product fromany suitable feed stream.

Reaction conditions within both the initial reaction zone and the tailzone may vary widely. Pressure for instance, may vary between 0 and900psig, preferably between 15 and 600 psig, and most preferably between50 and 500 psig. Temperature may vary between 600 and 1050F., preferablybetween 750 and 1,000" F., and most preferably between 780 and 980 F.The temperature and the pressure chosen will of course be a function ofthe particular feed stream utilized.

Hydrogen is circulated or recycled through the initial reaction zone andthe tail zone at a rate of 0 to 15,000 standard cubic feet (SCF) perbarrel (Bbl), preferably 1,000 to 10,000 standard cubic feet per barreland most preferably 2,000 to 6,000 standard cubic feet per barrel ofliquid naphtha feed.

The space velocity, which is expressed as weight in pounds of feedcharged per hour per pound of catalyst, depends upon the activity levelof the catalyst, the character of the feed stock and the desired octanenumber of the product. Ordinarily it may vary from about 0.2 W/Hr./W to20 W/Hr./W, preferably from about 0.5 W/Hn/W to about W/Hr./W and mostpreferably from about 1 to 5 W/l-Ir./W based on the total catalyst inthe system.

It is preferred to use the catalyst in the form of pellets or extrudateswhich are preferably one-sixteenth to one-fourth inch in diameter. v

In a preferred embodiment of the instant invention a train of fourcatalytic reforming reactors is utilized. The third and fourth reactors,i.e., the tail zone, contain a catalyst comprising platinum on analumina support. The catalyst comprises about 0.1 to 1.0 wt. percent ofplatinum and the remainder alumina and halogen, the latter ranging from0 to 2.0 wt. percent. The catalyst is prepared by impregnation of thealumina with an aqueous solution of chloroplatinic acid. It is thendried at about 220-250 F. and subsequently calcined in air at 4001,l00F. The finished catalyst is formed into pelletsof about lie-inch sizeand charged to the reforming reactors. In the first two reactors, i.e.,the initial reaction zone, there is the catalyst of the instantinvention, which comprises about 0.3 wt. percent platinum and 0.3percent Cu on alumina. The finished catalyst is used in the form of%-inch cylindrical pellets or extrudates of similar size. The amount ofcatalyst charged to the first two reactors is about 25 to 75 wt. percentof the total catalyst employed in all the reactors. Feed stream is anaphtha cut boiling between about 120 and 400 F. which comprises about15 to wt. percent paraffins, about 15 to 75 wt. percent naphthenes, andabout 2 to 20 wt. percent aromatics; weight hourly space velocity ofnaphtha feed is 0.5 to 10 pounds of feed per hour per pound of totalcatalyst in the system. Reactor temperatures and pressures are in therange of 700 to 1,000 F. and 100 to 500 psig, respectively. The hydrogenrecycle gas rate is 1,000 to 10,000 standard cubic feet per barrel ofnaphtha feed. The product issuing from the first two reactors containsabout 2 to 15 wt. percent naphthenes, the remainder comprisingparaffins, both normal and iso, and aromatics. After passage through thethird and fourth reactors containing the platinum catalyst, the productis separated into two fractions, one containing C and higher molecularweigh hydrocarbons and the other C and lower molecular weighthydrocarbons. The C fraction contains 60 to wt. percent aromatics, orhigher, with research clear octane numbers in the range of to 105, orhigher.

SPECIFIC EMBODIMENTS Example 1 Conversion of Naphthenes to AromaticsThis example demonstrates the superior ability of the catalyst of theinstant invention to convert alkylcyclopentanes to aromatics. A modelcompound, methylcyclopentane, was converted to benzene using a Pt-Cubimetallic catalyst* and the standard Pt catalyst. This experimentdemonstrates an important reaction occurring in the initial reactionzone of a catalytic reforming process. 7

Reaction Conditions Temperature 850 F.

Pressure 200 psig l-l /Methylcyclopentane mol ratio 5 Conversion 30 to40 percent Feed Methylcyclopentane Run Catalyst Composition Selectivityto Benzene A 0.3 wt. Pt on Alumina 27.0%

B 0.3 wt. 1; Pt on Alumina 42.0%

0.] wt. 61. Cu

C 0.3 wt. Pt on Alumina 55.0%

0.3 wt. Cu

D 0.3 wt. Pt 18.0%

0.6 wt. Cu

" A typical example of the catalyst preparation is illustrated thus:

PREPARATION OF THE CATALYST UTILIZED IN RUN C The proper amounts ofchloroplatinic acid and cupric nitrate to yield 0.06 gm of Pt and 0.06gm of Cu were dissolved in water, and the total aqueous solution volumewas brought to 13 cc.

Twenty gms of eta A1 0 were contacted with the solution and the mixturewas dried overnight at 220F. prior to charging to the reactor.

Note that optimum results are obtained with equal weights of Cu and Ptin the catalyst. Under these conditions the selectivity is twice that ofthe standard catalyst described in Run A.

Boiling range 190F. 315F.

Octane number 55.7 RON Paraffins 46.4

% Naphthenes 32.7

% Aromatics 16.7

was reformed under'the following conditions:

Temperature 940F.

Pressure 200 psig Space velocity 6 W/Hr./W

Catalyst 0.3% Pt on Al O The reaction product had a research octanenumber of 84.5. This material is then processed over a conventionalplatinum-alumina catalyst in the tail zone at 300 psig, at temperaturesof 900950 F. to yield a product with a research octane number of 98 orhigher.

What is claimed is:

1. A combination reforming process, wherein a hydrocarbon feed stream iscontacted in an initial reaction zone with a catalyst in the presence ofhydrogen, said catalyst consisting essentially of platinum and a metalselected from Group 18 of the Periodic Table of the elements, supportedon a refractory oxide, and subsequently led into a tail zone, whereinthe hydrocarbon feed stream is contacted with a catalyst, comprisingplatinum or alumina, and thereby further reacted.

2. The process of claim 1, wherein the hydrocarbon feed stream is anaphtha stock boiling in the range of 80 to 450 F. and comprisingparaffins, naphthenes, and aromatics.

3. The process of claim 2, wherein the said cent Pt and from about 0.05to about 2.0 percent Cu and the remainder support.

7. The process of claim 5, wherein the pressure in the initial reactionzone ranges from about 50 to 500 psi and the temperature ranges fromabout 750 to about 1 ,000 F.

8. The process of claim 7, wherein reforming takes place in the presenceof a hydrogen recycle of from naphthenes are substantially converted toaromatics in the initial reaction zone.

- 4. The process of claim 3, wherein the refractory oxide support isselected from the group consisting of 1,000 to 10,000 standard cubicfeet per barrel of naphtha feed.

. A process for catalytically reforming a hydrocarbon feed streamboiling between 80 and 450 F. and containing 15 to percent naphthenes,15 to 75 percent paraffms and the remainder aromatics, which comprisespassing said feed stream and a hydrogen-rich gas at a temperature offrom 600 to 1,050 F., a pressure of 15 to 600 psig, at a space velocityof 0.5 to 10 W/Hr./W, into a first catalytic reforming zone, said zonecontaining a supported catalyst consisting essentially of Pt and a metalselected from Group IB of the Periodic Table of the elements, wherebysaid naphthene content is decreased to a maximum level of about 15 wt.percent, passing the effluent from said first zone into a secondcatalytic reforming zone, said second zone comprising a Pt on aluminacatalyst, and recovering a product of high octane number.

10. The process of claim 9, wherein said Group IB metal is Cu.

11. The process ofv claim 9 wherein said catalyst of the first catalyticreforming zone consisting essentially of from about 0.05 to 2.0 percentPt, from about 0.05 to about 2.0 wt. percent Cu, and the remaindersupport.

12. A process for the conversion of naphthenes to aromatics whichcomprises contacting a naphtha feed stream, said naphtha feed streamcomprising from 15 to 75 percent by weight naphthenes with a catalystconsisting essentially of platinum and a metal selected from Group IB ofthe Periodic Table of the elements, supported on a refractory oxidesupport, said platinum comprising from about 0.05 to 2.0 weight percentand said Group 18 metal comprising from about 0.05 to 2.0 weight percentof the total catalyst, in the presence of hydrogen, at a temperature offrom 600 to l,050 F. and a pressure of from 15 to 600 psig, whereby saidnaphthenes are substantially converted to aromatics.

13. The process of claim 12 wherein said Group 18' metal is copper.

14. The process of claim 13 wherein said naphtha feed stream has aboiling point range of from to 450 F.

2. The process of claim 1, wherein the hydrocarbon feed stream is anaphtha stock boiling in the range of 80* to 450* F. and comprisingparaffins, naphthenes, and aromatics.
 3. The process of claim 2, whereinthe said naphthenes are substantially converted to aromatics in theinitial reaction zone.
 4. The process of claim 3, wherein the refractoryoxide support is selected from the group consisting of alumina,silica-alumina, acid treated alumina, and crystalline alumino-silicates.5. The process of claim 4, wherein the Group IB metal is Cu.
 6. Theprocess of claim 5, wherein the catalyst consisting essentially of fromabout 0.05 to about 2.0 percent Pt and from about 0.05 to about 2.0percent Cu and the remainder support.
 7. The process of claim 5, whereinthe pressure in the initial reaction zone ranges from about 50 to 500psi and the temperature ranges from about 750* to about 1,000* F.
 8. Theprocess of claim 7, wherein reforming takes place in the presence of ahydrogen recycle of from 1,000 to 10,000 standard cubic feet per barrelof naphtha feed.
 9. A process for catalytically reforming a hydrocarbonfeed stream boiling between 80* and 450* F. and containing 15 to 75percent naphthenes, 15 to 75 percent paraffins and the remainderaromatics, which comprises passing said feed stream and a hydrogen-richgas at a temperature of from 600* to 1,050* F., a pressure of 15 to 600psig, at a space velocity of 0.5 to 10 W/Hr./W, into a first catalyticreforming zone, said zone containing a supported catalyst consistingessentially of Pt and a metal selected from Group IB of the PeriodicTable of the elements, whereby said naphthene content is decreased to amaximum level of about 15 wt. percent, passing the effluent from saidfirst zone into a second catalytic reforming zone, said second zonecomprising a Pt on alumina catalyst, and recovering a product of highoctane number.
 10. The process of claim 9, wherein said Group IB metalis Cu.
 11. The process of claim 9 wherein said catalyst of the firstcatalytic reforming zone consisting essentially of from about 0.05 to2.0 percent Pt, from about 0.05 to about 2.0 wt. percent Cu, and theremainder support.
 12. A process for the conversion of naphthenes toaromatics which comprises contacting a naphtha feed stream, said naphthafeed stream comprising from 15 to 75 percent by weight naphthenes with acatalyst consisting essentially of platinum and a metal selected fromGroup IB of the Periodic Table of the elements, supported on arefractory oxide support, said platinum comprising from about 0.05 to2.0 weight percent and said Group IB metal comprising from about 0.05 to2.0 weight percent of the total catalyst, in the presence of hydrogen,at a temperature of from 600* to 1,050* F. and a pressure of from 15 to600 psig, whereby said naphthenes are substantially converted toaromatics.
 13. The process of claim 12 wherein said Group IB metal iscopper.
 14. The process of claim 13 wherein said naphtha feed stream hasa boiling point range of from 80* to 450* F.